Paralysed limbs move again

16 October 2008

Could a computer help paralysed people walk? A group of US scientists think so. They've used a simple but ground-breaking method to connect the brain directly to muscles, to allow movement.

This research was published in the online edition of the journal Nature on 15 October 2008.

Image: Chet Moritz

Paralysed limbs are caused by irreversible damage to nerves. The brain and muscles are still healthy, but they can't communicate with each other. For the first time, scientists from the University of Washington have recreated this
brain-muscle connection with a little help from computers.

Damage to the nerves in the spinal cord can leave you paralysed.

So what's the new method?
The scientists temporarily knocked out nerves in monkeys' arms using an anaesthetic. They hooked up the muscles at the end of these nerves to a computer. To complete the artificial circuit they linked the computer to the brain cells which normally control the arm muscles.

The anaesthetic was painlessly injected to temporarily paralyse the nerves.

Image: Dan Evans

Despite the fact that nerves between the brain and hand were out of action, the monkeys were able to move their arm normally just by thinking about it. The artificial circuit was doing the job of the nerves.
The research threw up a real surprise for the team. Any type of brain cell related to movement was able to move the monkey's arm - not just the brain cells that normally send signals to it.
Richard Apps, a brain scientist from the University of Bristol studies how the brain controls movement and agrees that the team's findings add to our knowledge:
'This research reflects the remarkable plasticity of the central nervous system and suggests the brain is far more flexible in its control than we previously realised.'
What's the next step?
Chet Moritz, one of the research team, hopes their research will be able to help people in future: 'Tiny computers could be implanted under the skin, like a pacemaker. Such technology may one day help paralysed people to move their arms and legs directly with their thoughts.'

Chet Moritz, brain scientist, University of Washington.

However, to make the scientists' ambitions a reality, they need to record the electrical signal from the nerves more accurately and computers will have to be made small enough to fit into the body.
But when these technologies are ready, perhaps in the next ten years, it could change the lives of paralysed people.
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